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A NEW SPECIES OF CCELASTRUM 
By FLORENCE RICH, M.A. 
(From the Botanical Department, East London College) 
I N making collections of algae from various pieces of water in 
Leicestershire a sample was gathered on April 26, 1915, from a 
very narrow ditch (choked with phanerogamic vegetation and much 
overhung with ivy, brambles, etc.) that bounds the garden of the 
large house known as Leicester Frith, situated on Boulder Clay over- 
lying Keuper Marl, on the Groby Road, near Leicester. When this 
was examined it was found to contain three species of Spirogyra, of 
which 5 . quadrata (Hass.) Petit was the commonest, Vaucheria 
sessilis (Vauch.) D.C., many diatoms, and numerous small colonies 
of cells which proved to belong to an interesting and apparently un¬ 
described species of Ccelastrum. Repeated attempts to obtain fresh 
supplies of material were unfortunately without success. In the 
original sample, however, there is a considerable amount of material 
available, and the organism can be observed in many different stages 
(of which a few have been figured). 
The coenobium of the new species of Ccelastrum consists of 2, 4, 8 
or more, rounded cells; perhaps 8 is the commonest number. Single 
cells are frequent, and apart from the typical Ccelastrum grouping 
irregular colonies occur (Fig. xv). The cells vary in size from ii/z 
to 14 /x in diameter. 
The coenobia are sometimes surrounded by a wide—or narrow— 
mucous investment with a well-defined boundary, but more often 
than not this investment is wanting. 
The cell-contents (in the preserved material) are light bluish green 
in colour, the smaller (? younger) cells showing a more yellowish tinge. 
The chloroplast has not been completely deciphered, but there 
appears to be one in the form of a convoluted plate. There seems to 
be one pyrenoid in each cell. The contents show the presence of 
plentiful starch. 
The cell-wall is laminated and is evidently rather mucilaginous 
as it is penetrated by methyl blue. 
Isolated cells are, roughly speaking, spherical in shape; when 
there are groups of two or more the cells, though still frequently 
